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Mold exposure in infancy linked to childhood asthma, study finds

While mold is considered an asthma trigger and risk factor for exacerbating asthma, new research links three mold species to childhood development of asthma, according to a study by University of Cincinnati researchers.

Infants who had higher values on an index that screened homes for 36 molds were associated with an increased asthma risk.

Researchers evaluated nearly 300 children at the ages of 1 and 7, and 24% were diagnosed with the chronic lung disease at the age of 7. About 12% of the children with asthma were allergic to mold and 58% were allergic to airborne substances at age 7.

Dust samples were collected when the children were 8 months old. They were all born between 2001 and 2003 in Cincinnati and northern Kentucky. At least one parent had allergies. There were no significant differences between the distributions of parental asthma, gender, race and income between the 289 children, according to researchers.

Tiina Reponen, co-author of the study, said while it is known that mold is a risk factor for asthma, this is the first study that quantitatively measured mold and after adjusting for commonly known risk factors, found an association with asthma. Previously, other studies had shown qualitative or anecdotal associations, she said.

“If you have visible mold or water damage - that is associated with the risk of asthma symptoms and all sorts of other respiratory (issues) like rhinitis (runny nose) and wheezing.”

Monica Vasudev, an allergist at the Medical College of Wisconsin who was not part of the study, said the research was unique in that it identified water-damaged homes, which should be addressed if expectant mothers and infants live such residences.

“We know that mold is ubiquitous; it’s present in the outdoor environment, especially in the indoor environment -- and it may not be obvious in the indoor environment,” Vasudev said.

The three mold species -- Aspergillus ochraceus, Aspergillus unguis and Penicillium variabile -- are common to water-damaged homes. According to the Centers for Disease Control and Prevention, new evidence links damp buildings and new onset of asthma.

Aspergillus unguis and Penicillium variabile are common indoor molds rather than outdoor molds, said Gary Steven, an allergist at the Allergy, Asthma & Sinus Center in Milwaukee. However, dust mite allergens are more common in households.

“Children that are allergic to dust mite(s) are 20 times more likely to develop asthma than kids who are not allergic to dust mite(s),” he said.

Steven, who was not part of the study, said it’s known that chronic exposure to allergens increases risk of asthma.

“It’s proof of common sense that you want to take care of mold in the home. It’s just proving that if you don’t do that, your kids are more likely to develop asthma," he said. "But the thing that isn’t common sense, I would have expected the same with dust mite and cat allergen.”

Reponen agreed. “If you look at previous studies, dust mite is a major allergen,” she said. “It was a little bit surprising, it didn’t even hold up in this final analysis.”

Children at age 1 who tested for endotoxin, dust mite, dog and cockroach allergens were not associated with having asthma, according to the study.

Unless children or adults are skin tested, their specific sensitivities are unknown, said Vasudev.

“This gives us more information that we need to identity potential allergens in the air that can cause worsening of asthma,” she said.

The study was partially funded by the U.S. Department of Housing and Urban Development, National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency.

The research was published in the Journal of Allergy and Clinical Immunology this month.